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Denver's 2017 Climate Year in Review

With 2016 ending under the influence of weak La Nina conditions, 2017 experienced the La Nina weakening further into the beginning of the year. By late winter and early spring of 2017, a neutral ENSO (El Nino - Southern Oscillation) environment had developed as the cold waters, especially over the eastern equatorial Pacific region, moderated slightly to near normal and these conditions persisted through the end of the year. 

For the weather parameters of precipitation and temperature in Denver, 2017 ended the year with below average precipitation with a total of 11.69 inches. This was 2.61 inches below the normal of 14.30 inches. As for temperatures, 2017 marked the 4th year in a row with an annual temperature above average.  The average annual temperature for 2017 was 52.8 degrees, which was 2.3 degrees above 146 Year average of 50.5 degrees or 2.4 degrees above the current NCEI 1981-2010 average 50.4.

 

 

 

May was the only month in 2017 with well above average precipitation. A cool mid-month storm system dropped the majority of the month's precipitation as May ended with a wet 3.66 inches of precipitation and ranked as the 26th all time wettest May in Denver's history. After a cool and wet May, stable high pressure over the central Rockies along with a late onset to the North American Monsoon provided very dry conditions for June and July. The combined months of June and July typically bring 30% (4.14 inches) of the annual precipitation to Denver. In 2017, those two month combined for only 0.80 inches while bringing a start the annual running deficit of precipitation. June ended as 20th driest in Denver's 146 year history followed by July dryness registering in for 13th driest. 

With temperatures and precipitation rebounding closer to average for August, September and October, November ended up well below normal as a persistent strong ridge of high pressure developed over the southwest United States. This ridge of high pressure persisted through the middle of December ahead of the seasons first bout of Arctic air ahead of the Christmas Holiday.

 

 

With temperatures starting out near average for January, well above average temperatures arrived for February and continued through March. February's warmth tied for 6th warmest in Denver's 146 years history with March ending as 3rd warmest. Temperatures through the rest of the spring, summer and early fall each registered near the monthly averages, however above average warmth returned again for November as the month came in 10th warmest.

 


With above average temperatures from February persisting into March, a moist but mild late March storm system primarily came in the form of rain across the lower elevations. With March's precipitation coming in near normal, snowfall was absent for the month with a mere Trace landing in Denver in a month which typically receives 20% of the season's snowfall. As a drier than normal April developed, a late month, warm springlike storm system brought a scant 2.4 inches in a month which typically receives 6.8 inches.

When 2017 ended, the average annual temperature for Denver finalized at 52.8 degrees, which is 2.4 degrees above the NCEI 1981-2010 annual average of 50.4 degrees. This ranks as 8th warmest in Denver`s 146 Year temperature history. The warmest year in Denver`s weather History was in 1934 with an average annual temperature of 54.8 Degrees. The coldest year was 1912 with an annual average of 47.6 degrees.

 

                       Denver's 146 year history of average annual temperatures from 1872 through 2017.